Three Democratic congressmen are investigating certain firms to determine if they set up “fake pharmacies” to obtain and resell drugs that are in critically short supply at sharply increased prices.

Rep Elijah E. Cummings (D, Md), ranking member of the House Committee on Oversight and Government Reform; Sen John D. Rockefeller (D, WVa), chairman of the Senate Committee on Commerce, Science, and Transportation; and Sen Tom Harkin (D, Iowa), chairman of the Senate Committee on Health, Education, Labor, and Pensions, sent letters on March 21 to 3 companies in Maryland and North Carolina, asking for documentation on how they bought and sold short-supply drugs.